Supplementary  Information    

High-­‐performance  flexible  energy  storage  and  harvesting  system  for  wearable  electronics  

Aminy  E.  Ostfeld,‡  Abhinav  M.  Gaikwad,‡  Yasser  Khan,  and  Ana  C.  Arias    Department  of  Electrical  Engineering  and  Computer  Sciences,  University  of  California,  Berkeley,  CA  94720,  USA.  

                                                                                       

 Figure   S1.   Battery   electrodes   after   100   charge/discharge   cycles   and   600   flexing   cycles.   Cross-­‐sectional  SEM  micrographs  of  LCO  (a),  and  graphite  (b)  electrodes,  respectively.  Topographical  SEM  micrographs  of  LCO  (c),  and  graphite  (d)  electrodes,  respectively.    

 Figure  S2.  Comparison  of  areal  energy  density  (mWh/cm2)  and  volumetric  energy  density  (mWh/cm3)  of  our  battery  with  other   flexible  batteries  based  on   lithium-­‐ion  chemistry   reported   in   the   literature.    The  energy  density  values  are  based  on  unpackaged  battery.      Table   S1.   Comparison   of   thickness,   areal   energy   density,   and   volumetric   energy   density   of   our   battery  with  other  flexible  batteries  based  on  lithium-­‐ion  chemistry  reported  in  the  literature.     Thickness  (µm)*   Areal  Energy  Density  

(mWh/cm2)  Volumetric  Energy  Density  (mWh/cm3)  

Stanford  Paper  Battery1   280.0   2.05   73.29  Textile  Battery2   450.0   0.75   16.76  Inorganic  Battery3   6.8   0.37   30.83  PRISS  Battery4   160.0   0.94   58.90  Serpentine  Battery5   500.0   2.42   48.30  Sprayed  Battery6   480.0   2.70   56.25  3D  Battery7   300.0   2.76   92.00  UCB  Battery   182.5   6.98   382.5    *Thickness  of  the  battery  without  packaging  

 Figure  S3.  Behavior  of  PV  module  and  battery  with  blocking  diode.  (a)  Current-­‐voltage  characteristics  of  PV   module   with   blocking   diode   in   the   dark   and   under   4.8   mW/cm2   illumination   from   a   compact  fluorescent   light   bulb.   (b)   Battery   charging   characteristics   under   same   illumination   condition.   In   the  shaded   region,   the   light   was   turned   off   but   the   battery,   PV   module,   and   diode   remained   connected  together.  The  blocking  diode  prevented  current  from  flowing  out  of  the  battery  into  the  PV  module.      References  1.   Hu,  L.,  Wu,  H.,  La  Mantia,  F.,  Yang,  Y.  &  Cui,  Y.  Thin,  flexible  secondary  Li-­‐ion  paper  batteries.  ACS  

Nano  4,  5843–5848  (2010).  

2.   Lee,  Y.-­‐H.  et  al.  Wearable  textile  battery  rechargeable  by  solar  energy.  Nano  Lett.  13,  5753–5761  (2013).  

3.   Koo,  M.  et  al.  Bendable  inorganic  thin-­‐film  battery  for  fully  flexible  electronic  systems.  Nano  Lett.  12,  4810–4816  (2012).  

4.   Kim,  S.-­‐H.  et  al.  Printable  solid-­‐state  lithium-­‐ion  batteries:  A  new  route  toward  shape-­‐conformable  power  sources  with  aesthetic  versatility  for  flexible  electronics.  Nano  Lett.  15,  5168–5177  (2015).  

5.   Xu,   S.   et   al.   Stretchable   batteries   with   self-­‐similar   serpentine   interconnects   and   integrated  wireless  recharging  systems.  Nat.  Commun.  4,  1543  (2013).  

6.   Singh,  N.  et  al.  Paintable  battery.  Sci.  Rep.  2,  481  (2012).  

7.   Sun,  K.  et  al.  3D  printing  of  interdigitated  Li-­‐ion  microbattery  architectures.  Adv.  Mater.  25,  4539–4543  (2013).